There is a strong demand for antibacterial products in recent years in reflection of the growing public interest in cleanliness in various aspects of their life.
Among items of household use, brush hairs (synthetic fibers) used in cosmetic tools such as cosmetic brushes, mascara brushes and other brushes are prone to attachment of sebum, grime, etc., on brush hairs because these brushes are used in a manner coming in direct contact with human hairs, skin, etc., while a liquid or solid cosmetic material is placed on them. When sebum, grime, etc., attach to brush hairs, miscellaneous bacteria and microorganisms grow and foul smell, moulds, etc., generate to create an unsanitary condition. Miscellaneous bacteria and microorganisms also grow on sanitary tools such as toothbrushes and make these tools unsanitary. Accordingly, various proposals have been made to prevent production and growth of miscellaneous bacteria and microorganisms.
Technologies to add antibacterial property to cosmetic tools, sanitary tools, etc., are generally classified into two means. One means of technologies is intended to form a cosmetic tool with brush hairs, etc., from a synthetic resin material, by retaining on the material, before it is processed further, a chemical agent having antibacterial property.
The other means of technologies is intended to use a solution of a chemical agent having antibacterial property to treat the surface of brush hairs or any brush member (such as the base, handle or shaft of the brush) made of a resin material or animal hairs.
Technologies in the former group include, for example, impregnating a chemical agent having antibacterial property into the sheath of hairs each having a two-layer structure constituted by the core and sheath (Patent Literature 1), impregnating one of various chemical agents having antibacterial property into brush hairs (Patent Literatures 2, 3), impregnating a zinc antibacterial agent into brush hairs (Patent Literature 4), and impregnating into brush hairs an inorganic antibacterial agent to which ions of titanium, zirconium or other metal have been added (Patent Literature 5).
Technologies in the latter group include, for example, using an appropriate material selected from alkyl ammonium salt, alkyl benzyl ammonium salt, alkyl pyridinium salt, etc., containing quaternary nitrogen, to give antibacterial treatment to brush hairs made of animal hairs (Patent Literatures 6, 7), and using an appropriate material selected from alkyl ester of parahydroxybenzoate, parachlorophenol, parachlorometacresol, parachlorometaxylenol, isopropyl methylphenol, etc., to give antibacterial treatment (Patent Literature 8).
Patent Literature 1: Japanese Utility Model Laid-open No. Hei 3-3226
Patent Literature 2: Japanese Patent Laid-open No. Hei 3-289905
Patent Literature 3: Japanese Patent Laid-open No. Hei 5-7510
Patent Literature 4: Japanese Patent Laid-open No. Hei 10-5044
Patent Literature 5: Japanese Patent Laid-open No. 2005-53973
Patent Literature 6: Japanese Patent Laid-open No. Hei 4-193103
Patent Literature 7: Japanese Patent Laid-open No. 2002-223857
Patent Literature 8: Japanese Patent Laid-open No. 2000-41730